Papers by Keyword: Cu Nanoparticles

Abstract: Waste cooking oils (WCOs) are widely considered in the scientific community as potential energy vector or source for bio-lubricants. This is because of the opportunity deriving from recycling and the difficulties in disposing of waste oils. Indeed, industrial plants for WCOs treatment include bio-refineries (bio-diesel, bio-lubricants, fine chemicals...) or simple recovery systems: the former ones assume triglycerides transformation into other compounds, according to the specific commercial destination; in the latter, triglycerides are preserved and the WCO is purified from by-products, formed during cooking process, in order to sell to the market. In an era scarred by CO₂ and petroleum dependency, biodegradable products, offer many advantages. In this scenario, nanostructured additives, which are pointed out as the step forward in lubricant technology, can exploit WCOs’ derivatives for compatibilization or as reactive components allowing improvements in nanolubricant fluids. This paper proposes a Cu nanoparticle-based additive, properly surface functionalized and prepared through a “wet chemistry” approach, to be involved in tribochemical reaction with epoxidized vegetable oil. The idea was to promote the formation of tribofilm under contact, exploiting energy generated during the movement.

Abstract: This article reports investigations on thermally stimulated third order nonlinear absorption in Cu-PVP nanocomposite thin films. Cu nanoparticles have been obtained using chemical reduction method and thin films of Cu-PVP nanocomposites have been obtained using spin coating technique. Thin films have been characterized by X-ray diffraction (XRD), Ultraviolet-visible (UV-vis) spectroscopy, Fourier infra-red (FT-IR) spectroscopy, etc. for structural and linear optical studies. Third order nonlinear absorption studies have been performed using open aperture z-scan technique under continuous wave (CW) He-Ne laser. Cu-PVP nanocomposites are found to exhibit strong nonlinear absorption coefficient stimulated by thermal lensing effect.

Abstract: The current research is aimed at obtaining suitable nanocomposites for bipolar plate application in fuel cell, which fulfill the requirement for electrical and mechanical properties and low production cost. For this purpose, copper nanoparticles (Cu-NPs) were embedded in polypropylene matrix through wet-chemistry technique with the presence of polypropylene-grafted maleic anhydride as the coupling agent. The resulting nanocomposites were characterized with UV-Vis spectroscopy, TEM, SEM, TGA and electrical conductivity measurement. It was found that the addition of Cu-NPs up to 1.50 wt% has improved effect on the electrical conductivity up to 14.43 S/cm. However, further increase of Cu-NPs loading to 2.00 wt% adversely reduced the electrical conductivity down to 9.31 S/cm, as a consequence of severe agglomeration and large pores formation.

Abstract: A simple and novel preparation method for Cu nanoparticles has been suggested in this work. Its main innovative thought lies in preparing nano-copper in liquid paraffin without addition of other reductant. The paraffin is cheap and nontoxic, and the copper nanoparticles prepared by this method are not oxidized when exposed to air at room temperature. The obtained nano-copper has been characterized by X-ray diffraction measurements (XRD), scanning electron microscopy (SEM), transmission electron microscope (TEM), and energy dispersive analysis of X-ray (EDX), X-ray photoelectron spectra (XPS), and Fourier transform infrared spectroscopy (FTIR). The TEM results confirm that the optimal average size of nanoparticles is about 20 nm. The effects of time, temperature and surfactant on the size of nano-copper have been investigated. The results show that the optimized conditions are reaction temperature of 250 oC and reaction time of 3 h. By this method, the raw materials are cheap and the process is simple, so it can be applicable to large-scale production of copper nanoparticles.

Abstract: Copper nanoparticles were successfully prepared in large scales by means of anodic arc discharging plasma method in inert atmosphere. The particle size, specific surface area, crystal structure and morphology of the samples were characterized by X-ray diffraction (XRD), BET equation, transmission electron microscopy (TEM) and the corresponding selected area electron diffraction (SAED). The experiment results indicate that the crystal structure of the samples is fcc structure as same as that of the bulk materials. The specific surface area is is 11 m2/g, with the particle size distribution ranging from 30 to 90 nm, the average particle size about 67nm obtained from TEM and confirmed from XRD and BET results. The nanoparticles have uniform size, higher purity, narrow size distribution and spherical shape can be prepared by this convenient and effective method.

Abstract: Oxidation behavior of Cu nanoparticles in the formation process of hollow Cu2O spheres was investigated by TEM. The thickness of Cu2O layers on Cu nanoparticles oxidized at 323 K in air was measured as a function of oxidation time. At the initial stage of oxidation until the oxide film with 2.5 nm in thickness is formed, the thickness of oxide films on Cu nanoparticles with the diameter of 10, 20 and 35 nm shows a nearly equal value regardless of diameter of Cu. After the formation of 2.5 nm layer, however, the growth rate of the oxide films on smaller nanoparticles becomes slower than that on larger nanoparticles. This result suggests that the voids formed at the Cu/Cu2O interface prevent Cu atoms from diffusing outward across the interface because the volume ratio of voids to inner Cu in smaller nanoparticles is much larger than that in larger nanoparticles.